InfiniteNESLives has definitely made a mapper 34 board. It's what the Lizard cartridges are built on.

I don't know if mapper 34 boards are offered for sale, but you can e-mail them to ask. The "coming soon" statement may be out of date. Otherwise you can run Lizard on a PowerPak, or an Everdrive N8, or there are other options like ReproX, but if you want something you can program easily with the flasher you got for NESMaker, you'll probably need a flashable board from InfiniteNESLives.

Thanks for clarifying what you're seeing. That process looks new to me, and I really don't understand why a connection to Steam has to be made. When I've claimed keys in the past on other games it was just a simple click that reveals the text of a key, unless I'm not remembering correctly. I gave keys to itch.io and they should be able to give them directly to you. :( I will contact support. I'm sorry this has happened.

Edit: apparently the first time you claim a Steam key on Itch.io it has to verify that you have a Steam account. After this it will just directly give you the key. The interface for this verification was temporarily broken, but has been fixed by Itch.io.

On your download page on itch.io there should be a link to "Claim Steam Key". Clicking it should give you a key (a 15 digit string), this link should not take you to any other website.

You can then copy that key, open the Steam client. Go to the Games menu at the top of the window and select "Activate a Product on Steam..." where you can paste that key.

I believe you can only activate a Steam key through the client application. There is no way I know of to do it through Steam's website. I'm not sure what link would take you there, or why?

If that doesn't work, you can let me know but if there's a problem with itch.io or Steam's services I don't have a lot of control over that, we may have to contact their support. Sorry about the inconvenience.

I took a look at my notes and code again and there is one caveat to that previous statement: if fullscreen is being applied on your second monitor on a two monitor system, it is forced to use the fake fullscreen overlay for that monitor. So the solution could possibly to change your primary monitor setting if it's a two-screen setup.

This application does request true fullscreen through SDL's video API. There is an alternative option for a borderless window that covers the screen, but Lizard does not use this.

So, Lizard should not be able to do anything besides true fullscreen, and I have verified this to be working correctly on all the machines I have available to me. Lizard's fullscreen might look similar to the fake windowed fullscreen, because it requests the same resolution size as the desktop.

I can't say with 100% certainty that it's working correctly for you, there's always unexpected possibilities when it comes to video drivers and libraries like SDL, but to the extent that I have control of it in code, it's asking for true fullscreen.